With advances in technology and transportation convenience, the propagation speeds of infectious diseases (e.g., SARS, avian flu, dengue fever and other diseases) are accelerated and become the challenges in today's world. Consequently, the medical laboratory scientists make efforts in providing an effective prevention strategy for rapidly detecting and confirming the suspected cases and early isolating or confirming the therapeutic treatment. In other words, a “real-time and in-situ detecting means” is an important issue to study infectious diseases.
Nowadays, the rapid screening immunology is widely used. Although the rapid screening immunology is able to conduct a preliminary screening within 30 minutes, its accuracy is only 30%˜60%. Moreover, since the rapid screening immunology is only suitable for detecting a small number of infectious diseases, the applications thereof are limited. A molecular detection method can provide high accuracy detection and analysis. However, since many large expensive machines are needed and complicated procedures are operated by professional persons, the molecular detection method can be used in a small number of large-scale research and development centers and clinical analysis laboratories.
“Chip laboratory” is a novel concept proposed in recent years. In the chip laboratory, different miniature detection devices are integrated into the same platform so as to achieve the purposes of point of care (POC) and in vitro diagnostics (IVD). Its essence is to construct a medical detecting platform with “small volume”, “high accuracy” and “real-time diagnostics”.
The conventional method of extracting nucleic acid usually uses chaotropic salt such as guanidium hydrochloride (GuHCl) to bind DNA onto a silica membrane of a spin column, and inhibitors such as GuHCl, ethanol and isopropanol that influence the subsequent DNA analysis are washed away by high speed centrifugation. However, the inhibitors in the chip microfluidic system result in many problems. For example, the PCR reaction is adversely affected. Another method for extracting nucleic acid uses a chitosan coating material. However, the chitosan coating material of the conventional method is only able to extract at most 150 ng of DNA, and the recovery is usually unsatisfied.
Therefore, there is a need of providing an improved nucleic acid extraction method in order to overcome the above drawbacks.